Millions of people in the New York region will have to do without electricity for 10 days or even longer, beleaguered utility companies said today.

Manhattan and Brooklyn residents served by underground wires can count themselves lucky: Their power will be back in about four more days, Con Ed said.

Among those who’ll wait longer are about 300,000 Con Ed customers in Staten Island, Brooklyn, Queens and the Bronx who are served by overhead power lines, which were blasted to smithereens by Sandy’s winds.

In all, about 660,000 Con Ed customers in the five boroughs were without power as of 6:30 p.m. — mostly in Manhattan, where 287,000 customers lost electricity. Another 185,000 Con Ed customers were without power in Westchester County.

Con Ed and other utilities in the region have issued a nationwide call for help. More than 200 utility crews from California-based Pacific Electric and Gas are among those headed to New York.

“Sandy is the largest storm-related outage in Con Ed history,” the company said. “Crews are working around the clock to access damage and restore power.”

Ninety percent of LIPA’s system on Long Island was without power today, and the utility offered no timetable for restoring power to its 939,000 blacked-out customers.

Gov. Cuomo had stern words for LIPA executives and their handling of power outages. “LIPA has had a very poor track record in restoring power,” he said.

In New Jersey, more than 2.5 million electric customers — 62 percent of the state — are without power, the US Department of Energy reported.

PSE&G, the Garden State’s biggest utility, said the damage from Sandy is twice as bad as from last year’s Hurricane Irene.

But none of the state’s utilities offered any estimates of how long it would take to get power restored.